A complete fully thin-film pv harvesting and power-management system on plastic with on-sheet battery management and wireless power delivery to off-sheet loads

Large-area electronics enables the creation of systems with transformational capabilities and form factors. Through the ability to integrate thin-film photovoltaics, batteries, and active transistors, complete power-management subsystems addressing a wide range of applications can also be created. We present, for the first time, a fully flexible system integrating amorphous silicon (a-Si) solar modules with Li-ion thin-film batteries and circuits that are based on a-Si thin-film transistors for battery management and wireless power delivery. A fabricated prototype of the entire system on a plastic sheet is demonstrated. Using a 240 cm² solar module under indoor lighting conditions (∼400 μW/cm ²), the system is measured to provide 1) dc power (∼1 mW) to on-sheet loads and 2) ac power (∼10 mW) to off-sheet loads through wireless transmission. Four Li-ion batteries are used for on-sheet energy storage with a battery-management system ensuring discharging at permissible levels, while imposing minimal off-state current (<360 nA).